Université Grenoble-Alpes, CEA, INSERM, CNRS, Unité de Biologie Cellulaire et Infection, Grenoble, France.
Unité de Biochimie des Interactions macromoléculaires, Département de Biologie Structurale et Chimie, CNRS UMR 3528, Institut Pasteur, Paris, France.
Nat Commun. 2021 Jun 29;12(1):4024. doi: 10.1038/s41467-021-24337-9.
Pseudomonas aeruginosa can cause nosocomial infections, especially in ventilated or cystic fibrosis patients. Highly pathogenic isolates express the phospholipase ExoU, an effector of the type III secretion system that acts on plasma membrane lipids, causing membrane rupture and host cell necrosis. Here, we use a genome-wide screen to discover that ExoU requires DNAJC5, a host chaperone, for its necrotic activity. DNAJC5 is known to participate in an unconventional secretory pathway for misfolded proteins involving anterograde vesicular trafficking. We show that DNAJC5-deficient human cells, or Drosophila flies knocked-down for the DNAJC5 orthologue, are largely resistant to ExoU-dependent virulence. ExoU colocalizes with DNAJC5-positive vesicles in the host cytoplasm. DNAJC5 mutations preventing vesicle trafficking (previously identified in adult neuronal ceroid lipofuscinosis, a human congenital disease) inhibit ExoU-dependent cell lysis. Our results suggest that, once injected into the host cytoplasm, ExoU docks to DNAJC5-positive secretory vesicles to reach the plasma membrane, where it can exert its phospholipase activity.
铜绿假单胞菌可引起医院获得性感染，尤其是在使用呼吸机或患有囊性纤维化的患者中。高致病性分离株表达磷脂酶 ExoU，这是 III 型分泌系统的效应蛋白，可作用于质膜脂质，导致膜破裂和宿主细胞坏死。在这里，我们利用全基因组筛选发现，ExoU 需要宿主伴侣蛋白 DNAJC5 才能发挥其致坏死活性。已知 DNAJC5 参与涉及正向囊泡运输的错误折叠蛋白的非常规分泌途径。我们表明，DNAJC5 缺陷的人细胞或敲低 DNAJC5 同源物的果蝇对依赖 ExoU 的毒力具有很强的抗性。ExoU 在宿主细胞质中与 DNAJC5 阳性囊泡共定位。阻止囊泡运输的 DNAJC5 突变（先前在成人神经元蜡样脂褐质沉积症中发现，这是一种人类先天性疾病）抑制了依赖 ExoU 的细胞裂解。我们的结果表明，一旦注入宿主细胞质，ExoU 就会与 DNAJC5 阳性分泌囊泡对接，以到达质膜，从而发挥其磷脂酶活性。
